JPH0684501B2 - Freon compressor lubricating oil - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a lubricating oil for a flon compressor, and particularly to reduce friction and wear of a sliding portion of a rolling piston type freon compressor and prevent seizure. Fluorocarbon compressor lubricating oil.

[Background of the Invention]

In recent years, in the field of CFC compressors used for air conditioners and refrigerators, due to the trend toward miniaturization and high performance, the conventional reciprocating type has been replaced with a rotary type represented by a rolling piston type. By adopting this rotary type, conventional ON, O
It became possible to adjust the cold power by controlling the rotation speed from the FF control.

FIG. 1A is a vertical sectional view of a rolling piston compressor, and FIG. 1B is a lateral sectional view thereof. In FIG. 1, 1 is a rotary shaft, 2
Is a roller, 3 is a cylinder, 4 is a vane, 5 is a lubricating oil, 6
Is a bearing, 7 is a suction pipe, 8 is a case, 9 is a motor, 10 is a discharge pipe, and 11 is a discharge valve.

By the way, in the rolling piston compressor, as shown in FIG. 1, the roller (2) driven by the eccentric rotating shaft (1) rotates in a state where a part of the roller (2) is in close contact with the inner wall of the cylinder (3), and the flon is Compress. The vane (4) for partitioning the low pressure chamber and the high pressure chamber moves up and down in a groove provided in the cylinder, and the lower end thereof is pressed against the roller by a spring. There is linear contact friction between the vane and the roller, and the linear pressure is large. On the other hand, the refrigerating machine oil (5) is pumped up by a centrifugal pump provided at the lower end of the rotary shaft and supplied to each sliding portion.

Compared to the conventional reciprocating type, this rotary type requires lubricating oil with excellent lubricity, that is, high load resistance and wear resistance, because the friction conditions of the sliding parts are more severe, and it has been the main It has been recommended that naphthenic mineral oil be blended with tricresyl phosphate, which is an extreme pressure additive.

Furthermore, since high speed rotation is added when it comes to the rotation speed control system,
In particular, the temperature of the CFC discharge portion becomes high, and a lubricating oil having good heat resistance as well as lubricity is required.

As a base oil for lubricating oil for this purpose, synthetic oils such as alkylbenzene, polyolefin and polybutene, which have excellent heat resistance, that is, chlorofluorocarbon coexistence stability, must be used instead of conventional mineral oils. However, since these synthetic oils do not contain any component acting as an extreme pressure agent such as sulfur compounds in mineral oils, they have the drawback of poor lubricity.

On the other hand, it has been attempted to add tricresyl phosphate, which is a general extreme pressure agent, but this extreme pressure agent accelerates the decomposition of freon and lowers the heat resistance of the synthetic oil, which is not preferable. In addition to these, various phosphorous acid triesters (JP-A-53-88007), phosphoric acid di- or triesters (JP-A-54-139608), or phosphorous acid mono- or di-esters (JP-A-55-92799) are also used as measures for improving lubricity. And the like. However, phosphoric acid-based esters bring about a decrease in heat resistance like tricresyl phosphate, while phosphorous acid-based esters do not impair heat resistance, but hydrolyze due to the inclusion of a small amount of water to cause corrosive wear. It has the drawback of causing it.

[Object of the Invention]

An object of the present invention is to provide a CFC compressor lubricating oil that reduces friction and wear of each sliding portion of a CFC compressor that controls the rotation speed.

[Outline of Invention]

The invention relates to at least one base oil selected from the group consisting of alkylbenzenes, polyolefins and polybutenes with a secondary phosphate, in particular the general formula: [Where R is an alkyl group having 8 to 18 carbon atoms, (R'O) is an ethylene or propylene oxide group, and n is an integer of 2 to 10]. ] A fluorocarbon lubricating oil containing a phosphoric acid ester of polyoxyalkylene alkyl ether represented by:

In the general formula, the alkyl group (R) includes groups such as octyl, isodecyl, lauryl, tridecyl, palmityl, stearyl, oleyl and the like. As the alkylene oxide, ethylene oxide is generally used, and the number of moles added to the unit is preferably about 4-10.

Conventional phosphoric acid esters including tricresyl phosphite are composed of alkyl and alkyl / allyl groups, and it was confirmed that both fluorocarbon coexistence stability and hydrolyzability are related to this group. As a result of various investigations on alternatives to the alkyl / allyl group, it was found that polyoxyalkylene alkyl ether is preferable. Further, a secondary phosphoric acid ester was selected from the viewpoint of the reactivity as an extreme pressure agent, and the present invention was completed.

This phosphate ester has the ability to act as an extreme pressure agent, while the alkylene oxide group bonded to the phosphorus molecule captures chlorine, which is a decomposition product of CFCs, and suppresses the decomposition of CFCs secondarily. Such a phosphoric acid ester can be obtained as a commercially available product (for example, Nikko Chemical Co., Ltd., trade name NIKKOL).

The proportion of the phosphoric acid ester to the base oil in the present invention is suitably 0.1 to 5 wt%, and the use of an oil blended within this range as a lubricating oil suppresses wear of the rotary CFC compressor. You can

It should be noted that a silicone oil-based defoaming agent, a phenol-based antioxidant, etc. may be added to the above oil as long as the object of the present invention is not impaired.

Example of Invention

Examples 1 to 3, Comparative Examples 1 to 7 Alkylbenzene having a viscosity at 40 ° C. of 60.1 cSt (manufactured by Sun Oil Co., Ltd., trade name ZerS1300), 26.4 cSt polyolefin (made by Mobil Petroleum, trade name Gargoyle SHC224) and 19.5.
cSt polybutene (made by Nippon Oil Co., Ltd., product name Nisseki Polybutene L
V-10) was mixed with a predetermined amount of a phosphoric acid ester of three kinds of polyoxyalkylene alkyl ether to prepare a lubricating oil.

With respect to these lubricating oils, friction characteristics using a Huarex test machine, CFC coexistence stability by a shield tube test, further hydrolyzability, and an actual machine test by a CFC compressor were performed.

For comparison, base oil alone (Comparative Examples 1 and 2) and base oil blended with tricresyl phosphate (Comparative Example 3,
6), dioctyl phosphate (Comparative Example 4), and dioctyl hydrogen phosphite (Comparative Example 5) were added, and the same test was conducted.

The pharex test here is in accordance with the method specified in ASTM D2670-67, in which the rotary shaft is sandwiched between two V-blocks in oil, a load of 250 lbs is applied, and pre-rotation is performed for 5 minutes. The load was increased until seizure, that is, a sharp increase in friction torque, was observed by the ratchet method, and the load at this time was determined as the seizure load.

In the shield tube test, 0.5 ml of the test oil is searched for in a pressure-resistant glass test tube with an inner diameter of 6 mm and a wall thickness of 3 mm, and iron, copper, and aluminum wires of φ1.6 × 30 mm are put in this as a solvent. This was cooled with liquid nitrogen, 0.5 mm of Freon 12 was detected, and the sealed one was heated at 175 ° C. for 960 hours. After heating, the container was opened and the amount of chlorine ions, which is a freon decomposition product in the oil and freon mixture, was measured.

As the hydrolyzability, the acid value increase value was measured when 50 ml of the sample oil sampled in a 100 ml beaker was allowed to stand for 10 days in a thermo-hygrostat at a temperature of 25 ° C and an RH of 80%. In these tests,
As a lubricating oil, it is necessary to have a high seizure load, a small amount of chlorine ions generated, and a small acid value increase value. As a test using an actual machine, a rotary CFC compressor (CFC 12 refrigerant, high pressure 15 atg, low pressure 1 atg operating condition) was continuously operated for about 6 months.

Obtained Farex test, shield tube test,
The results of the hydrolyzability test and the actual machine test are shown in Table 1. As is clear from Table 1, the known phosphoric acid ester blends are not compatible with the flon coexistence stability or the hydrolyzability although the seizure load is increased more than the base oil alone. On the other hand, the phosphoric acid ester of the polyoxyalkylene alkyl ether of the present invention is a balanced extreme pressure agent that does not inhibit the coexistence of CFCs and does not cause hydrolysis.

Further, as is apparent from Table 1, the CFC compressor to which the lubricating oil according to the present invention is applied has little wear of the vane and the sliding portion of the roller even after about 6 months of operation, and the chlorine ion generation amount in the oil. It has excellent characteristics compared to conventional combinations with lubricating oil.

[Effects of the Invention] According to the present invention, it is possible to improve the lubricating performance without impairing the Freon coexistence stability of the synthetic oil having good Freon coexistence stability, and particularly the rotational speed control system of the rotary Freon compressor. Has a remarkable effect on driving.

[Brief description of drawings]

FIG. 1 (A) is a schematic vertical sectional view of a rolling piston type CFC compressor, and FIG. 1 (B) is a schematic horizontal sectional view thereof. 1 ... Rotary axis, 2 ... Roller, 3 ... Cylinder, 4 ...
Vane, 5 ... Lubricating oil, 6 ... Bearing, 7 ... Suction pipe, 8
…… Case, 9 …… Motor, 10 …… Discharge pipe, 11 …… Discharge valve.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C10M 107: 08 137: 04) C10N 30:00 C 8217-4H 30:06 40:30 (72) Inventor Tomoe Takamura 4026 Kuji Town, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory, Ltd. (72) Inventor Toru Iizuka 800 Tomita, Ohira Town, Shimotsuga District, Tochigi Prefecture Hitachi Co., Ltd.Tochigi Plant

Claims (2)

[Claims] 1. A CFC lubricating oil comprising a secondary phosphate in at least one base oil selected from the group consisting of alkylbenzene, polyolefin and polybutene. 2. The secondary phosphate is of the general formula (Wherein R is an alkyl group having 8 to 18 carbon atoms, (R'O) is an ethylene or propylene oxide group, and n is an integer of 4 to 10) and is a phosphoric acid ester of a polyoxyalkylene alkyl ether. Lubricating oil for a CFC compressor according to item 1.